Nitrogen doping of carbon nanoballoons by radiofrequency magnetron plasma and evaluation of their oxygen reduction reaction activity

Abstract

Nitrogen‐doped carbon materials exhibit a catalytic activity, such as an oxygen reduction reaction (ORR). In this study, we performed nitrogen doping on a carbon nanoballoon (CNB), which is a nanometer‐sized carbon particle in the form of a hollow sphere made of graphite by radiofrequency (RF) magnetron plasma in a gas mixture of nitrogen and helium. Nitrogen‐doped CNBs (N‐doped CNBs) were prepared by different plasma irradiation conditions: the sample installation positions, input powers, and irradiation times. The samples were examined for chemical state by X‐ray photoelectron spectroscopy (XPS). Hydrodynamic voltammetry was used for the evaluation of the catalytic activity of a N‐doped CNB with a pyridinic N concentration of 0.4‐1.0 at.%. As a result, the onset potential was measured to be 0.13 V versus RHE (reversible hydrogen electrode), which was close to the previously reported data of highly oriented pyrolytic graphite (HOPG) with a pyridinic N concentration of 0.57 at.%, which was prepared by annealing under NH3.

Advance in Using Plasma Technology for Modification or Fabrication of Carbon‐Based Materials and Their Applications in Environmental, Material, and Energy Fields

“…[ 87 ] prepared a high‐performance ORR catalyst as a nanometer‐size nitrogen‐doped carbon nanoballoon (CNB) using an RF magnetron N 2 ‐He plasma to produce N‐doped CNBs. [ 87 ] The onset potential value of 0.13 V versus RHE was similar to the value obtained by highly oriented pyrolytic graphite (HOPG) electrodes. [ 88 ] The content of pyridinic N in CNB was 0.4–1.0 at%.…”